I live about 45 miles from the OKC TV broadcast towers and don't have too much frustration getting most of the digital stations from OKC using just indoor antennas. Probably being at a higher elevation than much of town helps. It's been real surprising to see the OKC analog channels all snowy and then tuning to the digital channels and finding reception picture perfect, aside from some occasional dropouts, especially during daytime. However, the ABC station doesn't come in as consistently well as the CBS, NBC and OETA stations. I think the problem is lack of transmitter power. The ABC DT station has only around 34kw vs up to 1000kw for some of the others. I don't know what to tell you about your situation unless you live in a difficult, low elevation area where TV reception doesn't work well. Stillwater has some bad down low areas for TV and FM reception, such as the strip.
When the atmospheric conditions get just right, most likely at night after dusk, the digital stations from Tulsa will come in. That doesn't happen often, but no surprise given that the Tulsa stations are around 75 miles away.
Suddenlink, the cable provider in Stillwater, does carry the Oklahoma City ABC digital channel.
Until I got an HDTV, I didn't realize some of the digital channels from Oklahoma City, such as TBN and OETA had a bunch of digital sub channels that cable wasn't providing, so I've been experimenting with indoor antennas in hopes of avoiding the much bigger hassle of installing an outdoor antenna. And then the requirement of a big outdoor antenna with rotator and amp to get the Tulsa stations as well, if desired, would just add to the expense and complexity.
For VHF, I use unamplified rabbit ears. For UHF, I use a Phillips amplified indoor/outdoor UHF only antenna mounted at ceiling level, purchased from Lowe's. Surprisingly, it's shaped like a book, rather than looking like a typical antenna. So it was real easy to conceal and avoid unsightliness by mounting it behind a tapestry that's above my fireplace. The antenna won't bring in the OKC ABC digital station, though, probably reflective that the ABC station may be the only one broadcasting digitally on VHF.